Organic evaporators are a tool for the production of organic light-emitting diodes (OLED). OLEDs are a special type of light-emitting diode in which the emissive layer comprises a thin-film of certain organic compounds. Organic light emitting diodes (OLEDs) are used in the manufacture of television screens, computer monitors, mobile phones and other hand-held devices for displaying information. OLEDs can also be used for general space illumination. The range of colors, brightness, and viewing angle possible with OLED displays are greater than that of traditional LCD displays because OLED pixels directly emit light and do not need a back light. Therefore, the energy consumption of OLED displays is considerably less than that of traditional LCD displays. Further, the fact that OLEDs can be manufactured onto flexible substrates results in further applications. A typical OLED display, for example, may include layers of organic material situated between two electrodes that are all deposited on a substrate in a manner to form a matrix display panel having individually energizable pixels. The OLED is generally placed between two glass panels, and the edges of the glass panels are sealed to encapsulate the OLED therein.
There are many challenges encountered in the manufacture of such display devices. OLED displays or OLED lighting applications include a stack of several organic materials, which are for example evaporated in a vacuum. The organic materials are deposited in a subsequent manner through shadow masks. For the fabrication of OLED stacks with high efficiency, the co-deposition or co-evaporation of two or more materials, e.g. host and dopant, leading to mixed/doped layers is beneficial. Further, it has to be considered that there are several process conditions for the evaporation of the very sensitive organic materials.
For depositing the material on a substrate, the material is heated until the material evaporates. Pipes guide the evaporated material to the substrates through nozzles. In the past years, the precision of the deposition process has been increased, e.g. for being able to provide smaller and smaller pixel sizes. In some processes, masks are used for defining the pixels when the evaporated material passes through the mask openings. However, shadowing effects of a mask, the spread of the evaporated material and the like make it difficult to further increase the precision and the predictability of the evaporation process.
In view of the above, an increased precision and predictability of evaporation processes for manufacturing devices having a high quality and precision is beneficial.